Lug strap



May 31, 1938.

H. M. BACON v 2,119,479

LUG-,STRAP Filed March l2, 1936 .2. @m4 4' ,IiHlHglllHlljHlgf,Nillllmllllirlll II l.. 1;H!!!fi-Ml.'iilil Patented May 31, 1938 UNITEDSTATES PATENT oFEicE LUG STRAP Henry Miles Bacon, Warren, Ohio, assignerto The Dayton Rubber Manufacturing Company, Dayton, Ohio, a corporationof Ohio Application March 12, 1936, Serial No. 68,534 2 Claims. (Cl.139-153) This invention relates more particularly to imand its lifewould be materially shortened. Parprovements in lug straps of laminatedconstructicularly in the case of straps constructed of fabtion whereinsuperposed plies of fabric are united ric and glue some layers of thefabric became by a bonding material to form the strap. stretched andothers became wrinkled so that Important objects of the invention are,to proonly the middle layers were in a normal condition 5 vide a verydurable lug strap of the said characof tension, with consequentconcentration of ter; to provide such a strap constructed for evenstress and injurious strain. Efforts were made distribution of workingstress throughout the difto overcome this defect but they involvedlaboriferent plies of fabric; to provide for improved ous and costlymethods of construction and failed simplified construction of the bendor bow porto avoid liability of flawed construction. The 10 tion of sucha strap; and to provide an improved employment of glue in the structureof the strap method of making a lug strap of the said lamiis alsoobjectionable for the reasons that the glue Hated tYDetends at times tosoften under the humidity of Other objects of the invention will appearherethe weave room and at other times it cracks under inafter. theshocks and flexure to which the strap is subl5 In the drawing, Fig; 1 isa perspective view of jected in service and in handling. a core memberemployed for winding thereon My invention overcomes the defects notedand a fabric sheet coated with a bonding material, provides a strong,durable lug strap and a conas a step in lug strap manufacture; vcnientand comparatively inexpensive method Fig. 2 a cross sectional viewI ofthe said core for manufacturing lug straps in large quantities 20 andshowing diagrammatically the fabric wound and with minimum liability offlawed constructherearound; tion. The invention also provides a lugstrap Fig. 3 a plan view of the sleeve formed by the made of suchmaterial as to render the strap wound fabric, with dot and dash linesindicating free from attack by rodents and having other the transversesevering of the sleeve to form a advantages Which Will appearhereinafter 25 multitude of double straps; In the manufacture of ,lugstraps embodying Fig. 4 a sectional view showing the molding of theimproved construction I select a wide sheet l a double lug strap; ofsquare-woven textile fabric with maximum Fig. 5 a transverse section onthe line 5 5 cf warp strength and with pick strength consistent Fig- 4;y with easy handling. Both sides of this sheet I 30 Fig 6 a plan View 0fa molded double strap; coat with a bonding material 2 which is prefer-Fig. '7 a perspective view of a finished single ably a rubbercomposition capable of being vui- Stlap; canized to a hard state andhaving a low viscosity Fig. 8 a partial sectional View similar to Fig.4, prior to vulcanization. Other bonding materials but on a centralplane at a right angle thereto, having the required therme-flowing andSetting 35 showing the molding cf a double lug strap with properties may`be employed but rubber is preintegral convex cushions within its bends;ferred, for reasons which Will appear hereinafter. Fig. 9 a detailsectional view of an end of the The Sheetl. Coated with the rubberCOmPOSimold core, taken on the line 9--9 of Fig, 8; and tion is woundaround a core 3 whose cross section Fig. 10 a perspective view of thelug strap with conforms substantially to the interior of an elon- 40such a convex cushion. gated loop such as would be defined by placingaLug straps in use heretofore have customarily two U-shaped lug strapsend to end. The side been made of leather or wood, bent into shape,edges of the core are rounded, as at 4, in accordor of canvas duck orticking. In the employance with the curvature of the interior of thement of the latter material it has been customary bend or bow of the lugstrap. An oak plank so 45 to roll the fabric spirally, cement it withglue and formed will serve satisfactorily for the core. As then bend andmold the roll so formed into the the sheet is wound it is keptsufficiently taut for desired U form. In the employment of any ofsmoothness, and the winding is continued to form said materials thebending thereof into U-shape a number of superposed plies sufficient tobuild materially impaired their strength owing to the the structure upto a desired thickness exceeding 5u fact that the material at theoutside of the bend that of the finished lug strap. The sheet shouldwould be stretched and the material at the intebe wound with its warpthreads or strands, desigrior of the bend would be compressed orcramped. nated W in Fig. 3, running straight lengthwise of Consequentlythe lug strap would be incapable of the windings, around the core 3.Thus the coat-- uniformly distributed resistance to working stre-ss edsheet l is formed into a flat, multi-ply sleeve with the plies lyingsmoothly one upon' another. 'I'his sleeve is removed from the core I andsevered along the transverse lines 5 equally spaced along the sleeve tothereby provide va multitude of elongated flat loops each conformingsubstantially to a pair of lug straps arranged end to end. Preferablythe width of these partly formed double straps cut from the sleeve, thatis, their Width between the lines 5l is about one thirtysecond of aninch finished strap.

Each double strap is next subjected to a molding and preliminaryvulcanizing operation. This molding and vulcanizing operation isperformed to mold the strap to the desired shape and cross sectionaldimensions, bond together the plies and vulcanize the rubber compositionto a preliminary soft rubber state.

In preparation for the molding and vulcanizing operation a mold core 6of steel or other suitable material is fitted into the loop defined bythe double strap. This the shape and dimensions desired for vtheinterior of the strap. As shown, and properly rounded ends. The strapand core are placed between opposed blocks 1 of a split mold. Saidblocks have in their opposed faces elongated cavities 8 with roundedends and conform exactly to the desired shape and dimensions of theexterior of the strap. The plane of separation of the blocks occurs atthel center of the bends of the.strap, and the dimensions of thecavities 8 and of the core 6 are so correlated that when the mold isclosed the space between the rounded ends'of the core and the roundedends of the cavities between the flat sides of the core and the flatbottoms of the cavities.

'I'he molding operation is performed under heat and pressure tovulcanize the liminary, soft rubber state. Due to the shape andproportions of the parts of the mold, when the mold is closed, the flat,leg-forming portions of the strap will be subjected to greatercompression than the bends of the strap, and excess bonding materialwill be flowed from said at portions into the bends. Thereby the bends,while also compressed, are made thicker and less dense than theleg-forming portions. 'I'he pressure throughout the entire strap issufficient to unite the plies intimately and evenly.

The molded double strap is next removed from the mold.' the core 6 iswithdrawn, the strap is cooled and excess, overflow rubber is trimmedoff. The double strap is severed in the middle to form two single strapsS. Also, the usual slots 9 are made in the legs of the strap eitherbefore or after severance. Finally the vulcanization of the rubber iscompleted to bring it to a, hard state, This may be done by l formedstraps to dry heat in a suitable oven.

The` employment of the materials and the method described produces asuperior strap which satisfies all service requirements. Hard rubber isa very satisfactory material because of its nonbrittle nature, its hightensile strength, its imperviousness to weave, room humidity and alsobecause rodents will not eat it. 'I'he arrangement of the fabric withits warp threads running of the strap contributes to tensile less thanthat desired for the materially exceeds the space rubber to a pre-`subjecting the completely is performed in a. manner to reduce liabilityof unevenness in the plies to a minimum. 'Ihe usual stretchingvof theplies at the outside of the bow of the strip and the cramping andbuckling of the plies at the inner side of the bow is entirely avoidedina simple manner by my preforming method. Substantially all fabric'pliesemployed in the structure of the strap extend continuously throughoutthe length of both legs of the strap andaround the bow. A desired excessthickness of the bow of the strap is obtained by flowing excess bondingmaterial into the bow. This avoids employment of short plies of fabricto build up the thickness of the bow. The thickened bow provides therequired cushioning effect. Also while of less density than the legs ofthe strap the bow has adequate total strength due to its increasedthickness.

Due to the fact that the fabric is coated upon both sides with therubber composition and due also to the fact that the composition isconfined in the molding operation the finished strap contains much moreof the composition than is required for mere bonding. It comprises alarge part of the strap, as shown, and forms a matrix enveloping thefabric. 'I'his matrix is hard, tough, non-friable, resilient andmoisture-impervious. It surrounds the individual threads of the fabricand is reinforced the fabric plies. v

If a plug, not shown. is required for the interior of the bow of thestrap it may be tted, drilled and riveted into place.

It is also possible to form a satisfactory convex cushion in the bow ofthe strap in. a very 'I'his maybe done as shown in F1g.,8 by provisionof a mold core 6a similar to the core 6 except that it has concave ends6b conforming to the desired shape of the cushion. The molding pressurecauses the fabric and excess bonding material to iill the concavities ofthe core and form the integral cushions l0. Otherwise the strap with theconvex cushion is formed in precisely the same manner as the strappreviously described.

What I claim is:

1. A lug strap comprising a U-shaped body formed of a moldablecomposition of controllable hardness having a rubber base, and amultiplicity of reinforcing plies of woven fabric laid in U-form, onewithin another successively Within4 v closed spaced warp threads runningstraight longitudinally of the strap, said moldable composition beingcompressed, molded and vulcanized and impregnating the fabric of theplies and forming a hard, tough, non-friable, resilient andmoisture-impervious matrix enveloping the plies and surrounding' theindividual threads of the fabric of the plies and reinforced by theplies throughout the entire strap, the number of plies in the bow beingthe same as in the legs, the moldable composition being of greaterthickness in the bow than in the legs of the strap, and the bow beingless hard than the legs.

2. A lug strap comprising a U-shaped body formed of a moldablecomposition of controllable hardness having a rubber base, and amultiplicity of reinforcing plies of. woven fabric laid in U- form, onewithin another successively within the U and evenly distributed inclosely spaced relation throughout the thickness of said body and eachthroughout the strap by ply extending the length of both legs of thestrap the plies and reinforced by the plies throughout and around thebow, said moldable composition the entire strap, the number of plies inthe bow being compressed, molded and vulcanized and being the same as inthe legs, the moldable comimpregnatng the fabric of the plies andforming position being of greater thickness in the bow a hard, tough,non-friable, resilient and moisturethan in the legs of the strap, andthe bow being 5 impervious matrix enveloping the plies and surless hardthan the legs;

rounding the individual threads of the fabric of HENRY MILES BACON.

